Diagnostic method, system and device for a rotorcraft drive system

ABSTRACT

There is a method, system, and device for diagnosing an anomaly of a monitored component in a drive train, the method including obtaining original data based on samples of a vibration signal and a tachometer signal; generating a time synchronous average vibration signal; processing the time synchronous average vibration signal to produce a frequency-domain spectrum; determining the complex magnitudes of the frequency-domain spectrum; selecting a sub-synchronous band of the complex magnitudes of the frequency-domain spectrum to generate a sub-synchronous spectrum; and determining the mean of the sub-synchronous spectrum to generate a condition indicator.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Patent Application No. 62/376,121, filed Aug. 17, 2016, which is incorporated herein by reference in its entirety.

BACKGROUND Technical Field

The present disclosure relates to a method, system, and device for diagnosing an anomaly in an aircraft drive system.

Description of Related Art

An aircraft, such as a rotorcraft or tiltrotor aircraft, may include one or more rotor systems. One example of a rotor system is a main rotor system. The main rotor system may generate aerodynamic lift to support the weight of the rotorcraft in flight and thrust to counteract aerodynamic drag and move the rotorcraft in forward flight. Another example of a rotorcraft rotor system is a tail rotor system. The tail rotor system may generate thrust in the same direction as the main rotor system's rotation to counter the torque effect created by the main rotor system. A rotor system may include a gearbox that transmits energy from a power source to the rotor blade.

The rotor and drive system may produce sinusoidal or oscillatory vibratory forces during operation. The vibrations can be monitored for diagnostic purposes. Some methods using cepstrum analysis and wavelet techniques have been proposed but these have limited use in most rotorcraft health and usage monitoring systems (“HUMS”) systems.

There is a need for an improved diagnostic system, method, and device for a drive system.

SUMMARY

In a first aspect, there is a method of diagnosing an anomaly of a monitored component in a drive train, the method including obtaining, by a device configured to diagnose an anomaly, original data based on samples of a vibration signal and a tachometer signal; generating, by the device configured to diagnose an anomaly, a time synchronous average vibration signal; processing, by the device configured to diagnose an anomaly, the time synchronous average vibration signal to produce a frequency-domain spectrum; determining, by the device configured to diagnose an anomaly, the complex magnitudes of the frequency-domain spectrum; selecting, by the device configured to diagnose an anomaly, a sub-synchronous band of the complex magnitudes of the frequency-domain spectrum to generate a sub-synchronous spectrum; and determining, by the device configured to diagnose an anomaly, the mean of the sub-synchronous spectrum to generate a condition indicator.

An embodiment includes the step of processing comprises performing a discrete Fourier transform (DFT).

In another embodiment, the method includes determining a plurality of condition indicators.

In one embodiment, the method includes, based upon the plurality of condition indicators, determining an unhealthy condition of the plurality of condition indicators.

In still another embodiment, the method includes identifying an unhealthy component.

In an embodiment, the method includes adjusting at least one of the operation and maintenance of the unhealthy component.

In yet another embodiment, the device configured to diagnose an anomaly includes a display; wherein the device provides a real-time indication of an anomaly in the monitored component.

In an embodiment, the method includes storing a history, by the device configured to diagnose an anomaly, of original data; wherein the history being stored before the diagnostic operation for the component is performed.

In a second aspect, there is a device configured to diagnose an anomaly of a monitored component in a drive train, the device including a memory configured to store original data of at least one of a vibration signal and a tachometer signal; one or more processors in communication with the memory, the one or more processors being configured to: obtain original data based on samples of the vibration signal and the tachometer signal; generate a time synchronous average vibration signal; process the time synchronous average vibration signal to produce a frequency-domain spectrum; determine the complex magnitudes of the frequency-domain spectrum; select a sub-synchronous band of the complex magnitudes of the frequency-domain spectrum to generate a sub-synchronous spectrum; and determine the mean of the sub-synchronous spectrum to generate a condition indicator.

In an embodiment, the processors are configured to determine a plurality of condition indicators.

In one embodiment, the processors are configured to, based upon the plurality of condition indicators, determine an unhealthy condition of the plurality of condition indicators; and identify an unhealthy component.

In another embodiment, the processors are configured to adjust at least one of the operation and maintenance of the unhealthy component.

In an embodiment, the device includes a tachometer and at least one accelerometer.

In another embodiment, the device includes a display; wherein the device provides a real-time indication of an anomaly in the monitored component.

In yet another embodiment, the original data is stored before the diagnostic operation for the component is performed.

In a third aspect, there is a system for diagnosing an anomaly of a monitored component in a drive train, the system including a rotorcraft comprising a body, a power train coupled to the body and comprising a power source and a drive train coupled to the power source; a tachometer coupled to the drive train; a vibration sensor system coupled to the drive train; and a diagnostic device associated with the vibration sensor system, the diagnostic device operable to: obtain original data based on samples of the vibration signal and the tachometer signal; generate a time synchronous average vibration signal; process the time synchronous average vibration signal to produce a frequency-domain spectrum; determine the complex magnitudes of the frequency-domain spectrum; select a sub-synchronous band of the complex magnitudes of the frequency-domain spectrum to generate a sub-synchronous spectrum; and determine the mean of the sub-synchronous spectrum to generate a condition indicator.

In an embodiment, the vibration sensor system comprises at least one accelerometer.

In a fourth aspect, there is a non-transitory computer-readable storage medium encoded with instructions that, when executed, cause one or more processors of a computing device to diagnose an anomaly of a monitored component in a drive train to: obtain original data based on samples of the vibration signal and the tachometer signal; generate a time synchronous average vibration signal; process the time synchronous average vibration signal to produce a frequency-domain spectrum; determine the complex magnitudes of the frequency-domain spectrum; select a sub-synchronous band of the complex magnitudes of the frequency-domain spectrum to generate a sub-synchronous spectrum; and determine the mean of the sub-synchronous spectrum to generate a condition indicator.

Other aspects, features, and advantages will become apparent from the following detailed description when taken in conjunction with the accompanying drawings, which are a part of this disclosure and which illustrate, by way of example, principles of the inventions disclosed.

DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the embodiments of the present disclosure are set forth in the appended claims. However, the embodiments themselves, as well as a preferred mode of use, and further objectives and advantages thereof, will best be understood by reference to the following detailed description when read in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side view of a rotorcraft, according to an example embodiment;

FIGS. 2A-2B shows exemplary diagnostic systems with a drive train system for a rotorcraft;

FIG. 3A is a perspective view of a gearbox in a drive train system; according to an illustrative embodiment;

FIG. 3B is a perspective view of a sensor mounted to the gearbox in FIG. 3A;

FIG. 3C is a perspective view of sensor mounted to a gearbox, according to an exemplary embodiment;

FIG. 3D is a perspective view of a tachometer and a vibration sensor mounted to a gearbox, according to an illustrative embodiment;

FIG. 3E, is a schematic side view of a tachometer; according to an illustrative embodiment;

FIGS. 4A-4B are flowcharts showing exemplary diagnostic methods, according to exemplary embodiments;

FIG. 5A-5C are graphs illustrating sub-synchronous spectrums, according to an illustrative embodiment;

FIG. 6 is a graph illustrating condition indicators determined from the sub-synchronous spectrums in FIGS. 5A-5C over a time history of a component degrading; and

FIG. 7 is a schematic block diagram of a computer system, according to an illustrative embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Illustrative embodiments of a method, system, and device for diagnosing an anomaly in an aircraft drive system are described below. In the interest of clarity, all features of an actual implementation may not be described in this specification. It will, of course, be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure

In the specification, reference may be made to the spatial relationships between various components and to the spatial orientation of various aspects of components as the devices are depicted in the attached drawings. However, as will be recognized by those skilled in the art after a complete reading of the present application, the devices, members, apparatuses, etc. described herein may be positioned in any desired orientation. Thus, the use of terms such as “above,” “below,” “upper,” “lower,” or other like terms to describe a spatial relationship between various components or to describe the spatial orientation of aspects of such components should be understood to describe a relative relationship between the components or a spatial orientation of aspects of such components, respectively, as the device described herein may be oriented in any desired direction.

Referring to FIG. 1 in the drawings, a rotorcraft 100 is illustrated. Rotorcraft 100 can include drive train system 110, main rotor blades 120, tail rotor blades 120′, a fuselage 130, a landing gear 140, and a tail member 150. Drive train system 110 may rotate blades 120 and/or blades 120′. Drive train system 110 and blades 120′ may collectively provide thrust in the same direction as the rotation of blades 120 so as to counter the torque effect created by blades 120.

Fuselage 130 represents the body of rotorcraft 100 and may be coupled to drive train system 110 such that drive train system 110 and blades 120 move fuselage 130 through the air. Landing gear 140 supports rotorcraft 100 when rotorcraft 100 is landing and/or when rotorcraft 100 is at rest on the ground. The tail member 150 represents the tail section of the aircraft and features blades 120′.

In the example shown in FIG. 1, drive train system 110 includes an engine 112, a gearbox 160, a main rotor mast 114, and a tail rotor drive shaft 116. Engine 112 supplies torque to the main rotor mast 114 via gearbox 160 for rotating of blades 120. Engine 112 also supplies torque to tail rotor drive shaft 116 for rotating of blades 120′. In the example of FIG. 1, gearbox 160 is a main rotor transmission system. Teachings of certain embodiments recognize, however, that drive train system 110 may include more or different gearboxes than gearbox 160 shown in FIGS. 1 and 2A-2B. Drive train system 110 may include a control system for selectively controlling the pitch of each blade 120 in order to selectively control direction, thrust, and lift of rotorcraft 100. Gears, bearings, main rotor mast, and tail rotor drive shaft, and other mechanical components or systems of drive train 110 produce vibrations due to contact and movement with other components during operation.

Rotorcraft 100 further comprises a diagnostic system 200 for detecting an anomaly of a monitored component configured to identify and alert an operator, technician, or manufacturer to vibratory anomalies that may reflect a malfunctioning gear, bearing or other drive system related component. It should be appreciated that teachings from rotorcraft 100 may apply to aircraft other than rotor, such as airplanes, tiltrotor, hovercraft, unmanned aircraft, to name a few examples, and may apply to other industries including, but not limited to, automotive, ships, and industrial applications involving fixed equipment with rotational elements. The embodiments herein are illustrated with regard to a drive train for a main rotor assembly on a rotorcraft; however, it should be appreciated that the embodiments may be adaptable to a tail rotor assembly.

Diagnostic system 200, as shown in FIGS. 2A-2B, can include a tachometer 210 and a vibration sensor system 212 coupled to the drive train 110 and a diagnostic device 230, as shown in FIGS. 1 and 2A-2B. The diagnostic device 230 can represent any form of computing device capable of implementing the techniques described in this disclosure, including a handset (or cellular phone), a tablet computer, a smart phone, or a desktop computer. Diagnostic device 230 is configured to diagnose an anomaly in the component or system being monitored and can be operated by a user. In one embodiment, as shown in FIG. 2A, diagnostic device 230 is disposed on a rotorcraft 100. In another embodiment, as shown in FIG. 2B, at least a portion of the diagnostic device 230 is disposed on the rotorcraft and can be implemented by one or more computers across one or more networks.

Referring now to FIGS. 3A-3D, vibration sensor system 212 can include one or vibration sensors 216 configured to measure at least one of vibration, sound, and/acoustic signals within and/or produced from the monitored component and/or system. In an embodiment, the vibration sensor is, includes, or is part of an accelerometer. In an embodiment, only one sensor is located on a gearbox to monitor the health of the drive train 110. For example, as shown in FIGS. 3A-3D, one or more vibration sensors can be coupled to the gearbox 160. In an embodiment, at least two, three, four, five, six or more vibration sensors 216 are provided to monitor the health of the monitored component or system. A further embodiment provides a plurality of sensors to monitor the health of the drive train 110 and/or a component thereof.

Vibration sensors 216 can comprise accelerometers configured to provide a signal output corresponding to the acceleration of the sensors 216 in various directions (e.g., fore-aft, lateral, and vertical directions). In other embodiments, vibration sensors 216 can comprise other types of sensors capable of measuring vibration of a drive train system 110, such as a single-axis sensor, a multiple-axis sensor, a piezo electric sensor (either integrated electronics or with separate charge converter), and a micro electro-mechanical system (MEMS) type of sensor, and the like. In an embodiment, the vibration sensors 216 are only accelerometers.

The vibration sensor 216 may be connected directly to the monitored component or system and may include a bracket attached to the vibration sensor 216. In an exemplary embodiment shown in FIGS. 3A-3B, vibration sensor 216 is mounted to bracket 218. Bracket 218 is coupled to gearbox case 162 with a fastener 220 (e.g., a bolt, pin, screw, etc). Vibration sensor 216 may be externally mounted directly to a monitored component or system. In illustrative embodiment shown in FIG. 3C, like features are identified by like numerals with a primed (′) suffix and new features are identified by new numerals, including a rotorcraft gearbox 160′ and gearbox case 162′, sensor 216′ is coupled via a direct mounting connection to gearbox case 162′. Vibration sensor 216′ is secured to an extended fastener 220′ having an extended length for receiving the vibration sensor 216′ thereon and also secures portions of the gearbox case 162′ or other components of the drive train 110 together.

One or more vibration sensors 216 can be disposed at one or more locations on drive train 110 to monitor the health of the drive system 110 or other rotational systems. Vibration sensor 216 can be coupled to at least one of a gearbox, a bearing housing, a hanger bearing housing, a swashplate bearing housing, an engine, a transmission gearbox, engine gearbox, an oil blower, an oil cooler, a main rotor mast, a tail rotor drive shaft, a rotating component in drive train system, and a rotating system in a drive train system. Sensor 216 can be disposed on, in, in a passage adjacent to, or, near the monitored component or system. In an embodiment, vibration sensor 216 is disposed on a gearbox adjacent to gears therein. In the exemplary embodiment shown in FIG. 3A-3B, the sensor 216 is disposed on the input of gearbox 160. In another embodiment shown in FIG. 3C, like features are identified by like numerals with a primed (′) suffix and new features are identified by new numerals, the sensor 216′ is disposed mid-case of gearbox 160′. In another illustrative embodiment shown in FIG. 3D, like features are identified by like numerals with a double primed (″) suffix and new features are identified by new numerals, shows a first sensor 216 a disposed on a left-hand input drive and a second sensor 216 b disposed on a right-hand input-drive. FIGS. 3A-3D are illustrative embodiments and not limiting examples showing the sensor system 212.

One or more tachometers may be used to detect rotational speed of a rotating component, e.g., a shaft, gear, and/or part of a bearing. Tachometer technologies include optical sensor based, hall sensor based, generator (e.g., coil sensor) based and other tachometer technologies known to those skilled in the art. A tachometer is configured to provide an output, e.g., a pulse, at a rate (e.g., pulses per revolution) that corresponds to (e.g., is proportional to) the rotational speed of the rotating component being monitored.

In some embodiments, tachometer 210 can be mounted to a gearbox case 162 and monitor the rotational speed of a gear tooth passage, as shown in FIG. 3D. In the illustrative embodiment shown in FIG. 3D, the tachometer 210 is disposed adjacent to the left-hand input drive of gearbox 160” targeting a bevel gear disposed therein. In another embodiment, shown in FIG. 3E, a tachometer 210′ can be mounted adjacent to a shaft or other rotating component of gearbox 160. Tachometer 210′ can include a tachometer body 211a mounted to a fixed portion of the gearbox 160 and an interrupter 211t mounted to a rotating shaft or other rotating component. An interrupter passage 211p is provided between the tachometer body 211a and the interrupter 211t. Tachometer body 211a can be coupled to the gearbox 160 by a tachometer mounting member 211m and secured thereon by a nut or other conventional fastener.

During operation, gearbox 160 may transmit power from a power source (e.g., engine 112) to the object(s) to be moved (e.g., components in the drive train 110), which produces vibrations, sounds, and/or acoustic signals. The tachometer 210 is configured to detect the rotational speed of a monitored component. The vibration sensor system 212 is configured to measure vibrations, sounds, and/or acoustic signals from the drive train 110. The tachometer 210 and vibration sensor system 212 send an output of original data (e.g., the measurements of the vibrations, sounds, and/or acoustic signals) to the diagnostic device 230. The detected original data can be analyzed to determine a condition of a monitored component.

Diagnostic device 230 is configured to implement the method 300 of diagnosing an anomaly of a monitored component in a drive train 110. Method 300, as shown in FIG. 4A, can include at least one or more of the following steps: a step of 310 obtaining original data based on samples of a vibration signal and a tachometer signal; a step 320 of generating a time synchronous average vibration signal based on the original data; a step 330 of processing the time synchronous average vibration signal to produce a frequency-domain spectrum; a step 340 of determining complex magnitudes of the frequency-domain spectrum; a step 350 of selecting a sub-synchronous band of the complex magnitudes of the frequency-domain spectrum to generate a sub-synchronous spectrum; a step 360 of determining the mean of the sub-synchronous spectrum to generate a condition indicator; a step 370 of identifying a condition indicator; a step 375 of determining a plurality of condition indicators; a step 380 of determining an unhealthy condition based upon the plurality of condition indicators; a step 385 of identifying an unhealthy component; a step 390 of adjusting at least one of the operation and maintenance of the unhealthy component.

Method 300 can include a step of 310 obtaining original data based on samples of a vibration signal and a tachometer signal. In an embodiment, diagnostic device 230 can select, or sample, at predetermined equal intervals of time measurements in the vibration signal and digitize the vibration signal to obtain a snapshot of original data. In an embodiment, diagnostic device 230 can select, or sample, at predetermined equal intervals of time measurements in the tachometer signal and digitize the tachometer signal to obtain a snapshot of original data. The vibration and tachometer signals need to be sampled at the same time but not necessarily at the same sample rate. It should be appreciated that the sampling rate and methods may be achieved using a wide variety of configurations; for example, the sampling rate can be modified for each different application (e.g., each different type of gearbox).

The original data is then processed in step 320 using time synchronous averaging (TSA) to generate a time synchronous averaged vibration signal. TSA is configured to provide a vibration signal average over a revolution of the monitored component.

Method 300 includes the step 330 of processing the time synchronous averaged vibration signal to produce a frequency-domain spectrum. An illustrative embodiment of method 300 is shown in FIG. 4B that shows the processing of the time synchronous averaged vibration signal at step 330′ is achieved by a discrete Fourier transform.

The method can include step 340 of determining complex magnitudes of the frequency-domain spectrum. An illustrative embodiment of a frequency domain spectrum 342′ is shown in FIG. 4B.

A frequency band of the resulting frequency-domain spectrum can then be selected in step 350 to identify a sub-synchronous spectrum. In an embodiment, the sub-synchronous spectrum is a spectral line band sub-synchronous to the synchronous gear mesh of the monitored component (e.g., below the synchronous gear mesh frequency). In an embodiment, the sub-synchronous spectrum is a sine spectrum. The selected frequency band defines a band of sub-synchronous frequencies of interest.

In an illustrative embodiment of step 350 is shown as step 350′ in FIG. 4B. FIG. 4B shows an illustrative sub-synchronous spectrum 344′ including two predetermined numbers that define the band's lower and upper frequencies as a fraction of the synchronous gear mesh frequency are 0.18 and 0.63. Two predetermined numbers, each between 0 and 1, define the band's lower and upper frequencies as a fraction of the gear mesh frequency of the monitored component. The 1 - - - n band identified in spectrum 344′ is identified as spectral line i that equals 1 of the band, where n is the spectral line i that equals n of the band (e.g., the band has total number n of spectral lines). The x-axis for the spectrum 344′ is the gear mesh frequency (GM). The y-axis for the spectrum 344′ is the M magnitude.

FIGS. 5A-5C illustrate first, second, and third sub-synchronous spectrums 344 a, 344 b, 344 c based on three successive snapshots of original data as a monitored component in a drive train degrades over time. The X axis in each of FIGS. 5A-5C represents frequency. The Y axis in each of FIGS. 5A-5C represents magnitude. The magnitude of energy at each spectral line of the second and third sub-synchronous spectrums 344 b and 344 c is greater than that of the first sub-synchronous spectrum 344 a. The magnitude of energy at each spectral line of the third sub-synchronous spectrum 344 c is even greater than in the second sub-synchronous spectrum 344 b, which indicates that the component is degrading further than at the point in time reflected by the sub-synchronous spectrum 344 b.

Method 300 includes step 360 of determining the mean of the sub-synchronous spectrum (MSBP). Step 360 of determining the mean can include the steps of summing the magnitude of the spectral lines in the sub-synchronous spectrum and a dividing by the number of spectral lines in the sub-synchronous spectrum. FIG. 4B illustrates an embodiment of step 360 as 360′ that includes a calculation for determining the MSBP, where M is the magnitude of the spectral lines, n is the number of the spectral lines in the band. In an embodiment, the MSBP identifies a condition indicator in step 370.

Once a condition indicator has been determined, steps 310, 320, 330, 340, and 350, 360, and 370 can be repeated to determine a plurality of condition indicators in step 375. Method 300 can include step 380 that is based upon the plurality of condition indicators, determining an unhealthy condition of the plurality of condition indicators. Step 380 can include displaying the plurality of condition indicators in a graphical representation and/or other methods for arranging a plurality of condition indicators. An illustrative embodiment of a plurality of condition indicators is shown in FIG. 6. The X axis represents time. The Y axis represents numerical range of the condition indicator. First, second, and third condition indicators 345 a, 345 b, 345 c are each determined from the corresponding first, second, and third sub-synchronous spectrums 344 a, 344 b, 344 c shown in FIGS. 5A-5C. The first condition indicator 345 a at the snapshot 1 point in time indicates the beginning of an unhealthy condition (e.g., the first condition indicator 345 a is more than several of the previous condition indicators), as compared to the previous condition indicators. The second and third condition indicators 345 b, 345 c increase substantially over time as compared to the first condition indicator 345 a. The second and third condition indicators 345 b, 345 c indicate an unhealthy condition of the monitored component.

Method 300 can include the step 385 of identifying an unhealthy component. In some embodiments, step 385 can also include identifying a particular type of defect. In some embodiments, the unhealthy component can include a plurality of unhealthy components. For example, the plurality of condition indicators can be used to identify a range of a healthy condition of the component being monitored. When the condition indicator increases above the range of the healthy condition, the condition indicator is in an unhealthy condition.

Method 300 can include the step 390 of adjusting at least one of the operation and maintenance of the unhealthy component. In an embodiment, the diagnostic device 230 analyzes the condition indicators, the identity of the unhealthy component, and/or the type of defect relating to the drive train 110 (health information) and identifies maintenance performed thereon. This analysis is done in order to assess the health of a particular monitored component and drive train 110. In an exemplary embodiment, the diagnostic device 230 may determine, based on the health information, that a monitored component is nearing failure, and generate an indication that the component requires maintenance. In an embodiment, the maintenance of an unhealthy component can be adjusted by determining when the unhealthy component should be repaired and/or replaced. An indication could be presented on a display, printed out on a hard copy, or may take the form of an automatically generated work order that identifies a necessary maintenance task for the drive train 110. In a particular embodiment, once the unhealthy component is identified, step 390 can include the pilot, crew, or other user remote from the aircraft adjusting the aircraft speed or other operational parameters to reduce, disengage or otherwise lessen the impact of the unhealthy component in the drive train 110 from damage and/or to reduce the likelihood of catastrophic failure during flight. In some embodiments, method 300 may predict upcoming replacement and/or repair times of an unhealthy component to ensure that the component is not replaced and/or repaired prematurely. Since the unhealthy component can be identified prior to failure using the systems, methods and devices descried herein, the unhealthy component can advantageously be repaired or replaced prior to damaging other components in the drive train 110.

Diagnostic system 200 may be installed on-board an aircraft 100 (as indicated in FIG. 2A), off-board (such as at a ground facility), or a combination of the two (as indicated in FIG. 2B). In an exemplary embodiment, when diagnostic system 200 is installed on-board aircraft 200, diagnostic system 200 can include a member 232 and a processor 234. In an embodiment, memory 232 is configured to store the output of original data indicative of the vibration, sounds, and/or acoustic signals over time. In an embodiment, the output of original data is stored in memory 232 at least before the diagnostic method 300 is initiated. Memory 232 represents any suitable storage mechanism and may store any data for use by a computer system. Memory 232 may comprise one or more tangible, computer-readable, and/or computer-executable storage medium. Examples of memory 232 include computer memory (for example, Random Access Memory (RAM) or Read Only Memory (ROM)), mass storage media (for example, a hard disk), removable storage media (for example, a Compact Disk (CD) or a Digital Video Disk (DVD)), database and/or network storage (for example, a server), and/or other computer-readable medium. In an embodiment, processor 234 is configured to process original data from the tachometer, 210, vibration sensor system 212 and/or memory 232.

Diagnostic system 200 can include or otherwise be operably associated with a health and usage monitoring system (HUMS) 250 and a display 260. In an embodiment, HUMS 250 can receive outputs from the processor 234 regarding the health condition of the monitored component or system. In one embodiment, display 260 can receive outputs from the processor 234 that provide a visual indication of real-time health condition of the monitored component or system. Accordingly, a pilot of the rotorcraft 100 can be alerted to the real-time health condition of the monitored component in the drive train 110.

In another embodiment, as shown in FIG. 2B, diagnostic system 200 can be implemented by one or more computer systems 236 across one or more networks 238 and accessible by a user 240. Diagnostic system 200, as shown in FIG. 2B, can be configured to store original data related to the monitored component or system in memory 232. In an embodiment, the output of original data is stored in memory 232 at least before the original data is transmitted to one or more computers 236. The original data obtained by tachometer 210 and vibration sensor system 212 is transferred to one or more computer systems 236, typically after each flight. Computers systems 236 can be fixed or mobile on a ground station at various locations (e.g., an airport, military base, command center, manufacturer). The original data can be transferred over network 238 and/or using physical cabling or media; for example, but not limited to, hardwire cabling such as parallel cables, serial cables, USB cables, Firewire cables or the like or wireless protocols such as Bluetooth connectivity, infrared connectivity, radio transmission connectivity, Wi-Fi connectivity, other suitable communications protocol, removable memory cards, flash memory mass device, solid-state floppy disk card, non-volatile memory card, or other suitable memory storage entity.

Diagnostic system 230 can include computer system 236 as shown on FIG. 7. Computer system 236 can include an input/output (I/O) interface 242, an analysis engine 244, and a database 246. Alternative embodiments can combine or distribute the input/output (I/O) interface 242, analysis engine 244, and database 246, as desired.

Embodiments of system 236 can include one or more computers that include one or more processors and memories configured for performing tasks described herein. This can include, for example, a computer having a central processing unit (CPU) and non-volatile memory that stores software instructions for instructing the CPU to perform at least some of the tasks described herein. This can also include, for example, two or more computers that are in communication via a computer network, where one or more of the computers include a CPU and non-volatile memory, and one or more of the computer's non-volatile memory stores software instructions for instructing any of the CPU(s) to perform any of the tasks described herein. Thus, while the exemplary embodiment is described in terms of a discrete machine, it should be appreciated that this description is non-limiting, and that the present description applies equally to numerous other arrangements involving one or more machines performing tasks distributed in any way among the one or more machines. It should also be appreciated that such machines need not be dedicated to performing tasks described herein, but instead can be multi-purpose machines, for example computer workstations, that are suitable for also performing other tasks.

The I/O interface 242 can provide a communication link between external users, systems, and data sources and components of the system 236. The I/O interface 242can be configured for allowing one or more users 240 to input information to the system 236 via any known input device. Examples can include tachometer 210, vibration sensor system 212, memory 232, a keyboard, mouse, touch screen, and/or any other desired input device. The I/O interface 242 can be configured for allowing one or more users to receive information output from the system 236 via any known output device. Examples can include a display monitor, a printer, and/or any other desired output device. The I/O interface 242 can be configured for allowing other systems to communicate with the system 236. For example, the I/O interface 242 can allow one or more remote computer(s) to access information, input information, and/or remotely instruct the system 236 to perform one or more of the tasks described herein. The I/O interface 242 can be configured for allowing communication with one or more remote data sources.

For example, the I/O interface 242 can allow one or more remote data source(s) to access information, input information, and/or remotely instruct the system 236 to perform one or more of the tasks described herein.

The database 246 provides persistent data storage for system 236. While the term “database” is primarily used, a memory or other suitable data storage arrangement may provide the functionality of the database 246. In alternative embodiments, the database 246 can be integral to or separate from the system 236 and can operate on one or more computers. The database 246 preferably provides non-volatile data storage for any information suitable to support the operation of the system 236, including various types of data discussed further herein.

The analysis engine 244 can be configured for implementing at least one step in method 300. The analysis engine 244 can include various combinations of one or more processors, memories, and software components.

The device, system, and methods described herein can advantageously provide at least one of the following benefits: (1) the capability to collect and record vibrational information about aircraft components and systems during operation; (2) the capability to determine which component in the drive train is failing earlier than some conventional diagnostic systems; (3) determine when a component in the drive train should be replaced or repaired prior to failure, which can prevent further damage to adjacent components; and (4) the ability to adjust the operation of the aircraft to lessen the impact of the unhealthy component in the drive train on the safety of the flight and damage to other components in the drive train.

The particular embodiments disclosed above are illustrative only, as the apparatus may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of teachings herein. Modifications, additions, or omissions may be made to the apparatuses described herein without departing from the scope of the invention. The components of the apparatus may be integrated or separated. Moreover, the operations of the apparatus may be performed by more, fewer, or other components.

It may be advantageous to set forth definitions of certain words and phrases used in this patent document. The term “couple” and its derivatives refer to any direct or indirect communication between two or more elements, whether or not those elements are in physical contact with one another. The terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation. The term “or” is inclusive, meaning and/or. The phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like. The terms “a” and “an” are defined as one or more unless this disclosure explicitly requires otherwise.

Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the application. Accordingly, the protection sought herein is as set forth in the claims below. 

What is claimed is:
 1. A method of diagnosing an anomaly of a monitored component in a drive train, the method comprising: obtaining, by a device configured to diagnose an anomaly, original data based on samples of a vibration signal and a tachometer signal; generating, by the device configured to diagnose an anomaly, a time synchronous average vibration signal; processing, by the device configured to diagnose an anomaly, the time synchronous average vibration signal to produce a frequency-domain spectrum; determining, by the device configured to diagnose an anomaly, the complex magnitudes of the frequency-domain spectrum; selecting, by the device configured to diagnose an anomaly, a sub-synchronous band of the complex magnitudes of the frequency-domain spectrum to generate a sub-synchronous spectrum; and determining, by the device configured to diagnose an anomaly, the mean of the sub-synchronous spectrum to generate a condition indicator.
 2. The method according to claim 1, wherein the step of processing comprises performing a discrete Fourier transform (DFT).
 3. The method according to claim 1, further comprising: determining a plurality of condition indicators.
 4. The method according to claim 3, further comprising: based upon the plurality of condition indicators, determining an unhealthy condition of the plurality of condition indicators.
 5. The method according to claim 4, further comprising: identifying an unhealthy component.
 6. The method according to claim 5, further comprising: adjusting at least one of the operation and maintenance of the unhealthy component.
 7. The method according to claim 1, wherein the device configured to diagnose an anomaly further comprises: a display; wherein the device provides a real-time indication of an anomaly in the monitored component.
 8. The method according to claim 1, further comprising: storing a history, by the device configured to diagnose an anomaly, of original data; wherein the history being stored before the diagnostic operation for the component is performed.
 9. A device configured to diagnose an anomaly of a monitored component in a drive train, the device comprising: a memory configured to store original data of at least one of a vibration signal and a tachometer signal; one or more processors in communication with the memory, the one or more processors being configured to: obtain original data based on samples of the vibration signal and the tachometer signal; generate a time synchronous average vibration signal; process the time synchronous average vibration signal to produce a frequency-domain spectrum; determine the complex magnitudes of the frequency-domain spectrum; select a sub-synchronous band of the complex magnitudes of the frequency-domain spectrum to generate a sub-synchronous spectrum; and determine the mean of the sub-synchronous spectrum to generate a condition indicator.
 10. The device according to claim 9, wherein the processors are configured to: determine a plurality of condition indicators.
 11. The device according to claim 10, wherein the processors are configured to: based upon the plurality of condition indicators, determine an unhealthy condition of the plurality of condition indicators; and identify an unhealthy component.
 12. The device according to claim 11, wherein the processors are configured to: adjust at least one of the operation and maintenance of the unhealthy component.
 13. The device, further comprising a tachometer and at least one accelerometer.
 14. The device according to claim 9, wherein the device further comprises: a display; wherein the device provides a real-time indication of an anomaly in the monitored component.
 15. The device according to claim 9, wherein the original data is stored before the diagnostic operation for the component is performed.
 16. A system for diagnosing an anomaly of a monitored component in a drive train, the system comprising: a rotorcraft comprising a body, a power train coupled to the body and comprising a power source and a drive train coupled to the power source; a tachometer coupled to the drive train; a vibration sensor system coupled to the drive train; and a diagnostic device associated with the vibration sensor system, the diagnostic device operable to: obtain original data based on samples of the vibration signal and the tachometer signal; generate a time synchronous average vibration signal; process the time synchronous average vibration signal to produce a frequency-domain spectrum; determine the complex magnitudes of the frequency-domain spectrum; select a sub-synchronous band of the complex magnitudes of the frequency-domain spectrum to generate a sub-synchronous spectrum; and determine the mean of the sub-synchronous spectrum to generate a condition indicator.
 17. The system according to claim 18, wherein the vibration sensor system comprises at least one accelerometer.
 18. A non-transitory computer-readable storage medium encoded with instructions that, when executed, cause one or more processors of a computing device to diagnose an anomaly of a monitored component in a drive train to: obtain original data based on samples of the vibration signal and the tachometer signal; generate a time synchronous average vibration signal; process the time synchronous average vibration signal to produce a frequency-domain spectrum; determine the complex magnitudes of the frequency-domain spectrum; select a sub-synchronous band of the complex magnitudes of the frequency-domain spectrum to generate a sub-synchronous spectrum; and determine the mean of the sub-synchronous spectrum to generate a condition indicator. 